Yes, it is still trespassing on another person's property
Whether they realize it or not. ALL persons are affected by crime in one way or another.
Sounds fraudulent to me.
Leaving ANYTHING except US mail on, or in, a mailbox is a violation of US Postal Regulations.
Check their official website. It is a Federal crime to take anything out of another's mailbox, unless you are expressly permitted by the owner of the box to do so. Tampering with mail of others, even if it is sent to you by mistake, is also a crime. That goes for Postal Employees and civilians. If you have a newspaper box attached to your mailbox, it is not illegal to put things in it.
What kind of mailbox? A residential mailbox? A rural delivery mailbox? A mailbox in a parcel store? An official USPS mailbox? All are offenses, the last one especially. The fact that it turned out to be empty is immaterial. You didn't know it was empty when you broke into it, your intent was to open it and gain access to whatever was inside.
Yes.
It violates postal rules and it could certainly open one up to law suits.
Yes.Yes.Yes.Yes.
Theft Identity Theft is the Number One crime in America. Identity Theft is also the most lucrative and fastest growing crime.
This depends on how much money was stolen and where the crime was committed (which country or state)
It is an example of a "crime against persons."
I don't know about the "degree" of it, but it is classified as a "Crime Against Persons."